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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: tìm x biết : a) 4x^2-9-x(2x-3)=0 ; b) 4x^2-12x + 9 =0

Toán Lớp 8: tìm x biết : a) 4x^2-9-x(2x-3)=0 ; b) 4x^2-12x + 9 =0

Comments ( 2 )

  1. a) 4x^2-9-x(2x-3)=0
    4x^2 – 2x^2 + 3x – 9 = 0
    2x^2 + 3x – 9 = 0
    2x^2 – 3x + 6x – 9 =0
    x(2x – 3) + 3(2x – 3) = 0
    (2x-3)(x+3)=0
    ⇒ \(\left[ \begin{array}{l}2x-3=0\\x+3=0\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x=3/2\\x=-3\end{array} \right.\) 
    b) 4x^2 – 12x+9=0
    4x^2 – 6x – 6x + 9 =0
    2x(2x – 3) – 3(2x – 3)=0
    (2x-3)(2x-3)=0
    (2x-3)^2 = 0
    ⇒ 2x-3 = 0
    2x = 3
    x=3/2

  2. Đáp án:
     
    Giải thích các bước giải:
     

    toan-lop-8-tim-biet-a-4-2-9-2-3-0-b-4-2-12-9-0

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222-9+11+12:2*14+14 = ? ( )